World War II was a global military conflict that took place between 1939 and 1945. It was the largest and deadliest war in history. The conventional view is that the war began on September 1, 1939, when Nazi-led Germany invaded Poland. Within two days the United Kingdom and France declared war on Germany, forming the Allied Powers of Poland, the United Kingdom, France, and others. In September, 1940 Germany, Italy, and Japan signed a mutual defense agreement, the Tripartite Pact, and were known as the Axis Powers. In June 1941, Germany invaded the Soviet Union, forcing the Soviets into the Allied Powers. In December 1941, the Empire of Japan bombed Pearl Harbor the United States bringing it too into the war on the Allied side. China also joined the Allies, as eventually did most of the rest of the world. Italy surrendered in September 1943, Germany in May 1945. The surrender of Japan marked the end of the war, on September 2, 1945.